The elbow joint is an important pivot for the transmission of stress from the hand and forearm to the shoulder and trunk, and its main movements include flexion, extension, and forward and backward rotation in combination with forearm movements. The normal flexion angle of the elbow joint in most people is about 135°-160° active and 140°-170° passive; the straightening angle is about -10°-0° active and passive; the pre-rotation angle is about 80° active and 90° passive; and the post-rotation angle is about 80° active and 90° passive.